The association between self-reported versus nicotine metabolite-confirmed smoking status and coronary artery calcification

Objective There are no data comparing the relationship between coronary artery calcification and self-reported and cotinine-verified smoking. This study was carried out to evaluate the relationship between coronary artery calcium (CAC) and urinary cotinine or self-reported smoking status in Korean adults. Participants and methods Study participants included 22 797 individuals (19 181 men; mean age ± SD 39.2± 7.1 years) who were enrolled in the Kangbuk Samsung Health Study and Kangbuk Samsung Cohort Study between 2011 and 2013, and who had urinary cotinine and CAC measurements. Cotinine-verified current smokers were defined as having a urinary cotinine level of above 50 ng/ml. Results The prevalence of never smokers, former smokers, and current smokers according to the self-reported questionnaires was 44.6, 24.2, and 31.2%, respectively, and that of cotinine-verified current smokers was 30.2%. The prevalence of the presence of CAC in self-reported current smokers was higher than that in self-reported never/former smokers (13.7 vs. 10.2%, P<0.001), and that in cotinineverified current smokers was higher than that in cotinineverified never smokers (14.0 vs. 10.2%, P<0.001). A multivariate logistic regression model adjusted for the variables with univariate relationships showed that selfreported former smokers and current smokers had significantly increased odds ratio (OR) for the presence of CAC compared with self-reported never smokers [OR (95% confidence interval): 1.20 (1.03-1.40) in former smokers and 1.29 (1.11-1.50) in current smokers]. Cotinine-verified current smokers also showed a significant association with the presence of CAC [1.23 (1.12-1.35)]. Furthermore, logtransformed cotinine levels increased the OR for the presence of CAC [1.03 (1.01-1.05)]. Conclusion This study is the first large cohort study to show that both self-reported and cotinine-verified smoking is associated independently with the presence of CAC in Korean adults.